摘要
作为一个重要的转录调控因子,胰腺癌中甲基化 CpG 结合域蛋
白 1(methyl-CpG binding domain protein 1 ,MBD1)介导的甲基化
转录抑制作用可能是造成众多抑癌基因转录表达下降,以至失活的重
要原因。探讨 MBD1 在胰腺癌中的表达、调控及其作用有重要的研
究价值。
实验研究通过 RT-PCR 检测 MBD1mRNA 在两株胰腺癌细胞株
AsPC-1 和 BxPC-3 中的表达,发现均有较高水平的基础表达。BxPC-3
为原发癌细胞株,而 AsPC-1 具有很高的淋巴结转移侵袭活性,并同
时具有原发癌的生物学特性,因此选择 AsPC-1 细胞株作为研究平台,
探讨 MBD1 的表达、意义和调控。我们利用 RNA 干扰技术,设计合
成了针对 MBD1 基因的 siRNAs,并在其上下游分别引入 BgLⅡ和
HindⅢ限制性酶切位点,通过双酶切连接反应将 MBD1siRNAs 插入
质粒载体 Rotro Super 多克隆位点中的 BgLⅡ和 HindⅢ之间,从而成
功构建 MBD1siRNAs 真核表达质粒 Rotro Super-MBD1siRNAs,应用
RT-PCR 行酶切鉴定,结果显示 MBD1siRNAs 能成功载入质粒。采用
脂 质 体 介 导 的 方 法 将 MBD1siRNAs 表 达 质 粒 转 染 胰 腺 癌 细 胞 系
AsPC-1,通过 G-418 的筛选获得稳定表达 MBD1siRNAs 的阳性克隆。
应用RT-PCR和Western-blot方法检测AsPC-1细胞中MBD1在基因水
平和蛋白水平的表达变化,采用克隆形成实验和MTT法检测肿瘤细胞
增殖能力,利用多点微列阵技术观察甲基化相关基因表达的变化。研
究结果显示MBD1siRNAs表达质粒能显著抑制胰腺癌细胞AsPC-1中
MBD1mRNA 的表达,且 MBD1在蛋白水平亦受到明显抑制;克隆形成
实验和MTT测定生长曲线显示细胞生长受到显著抑制,表明MBD1siRNAs能抑
制胰腺癌的细胞增殖能力,降低肿瘤细胞的独立生存能力;利用多点微列阵杂
交发现在MBD1 mRNA表达下降的同时,其它甲基化相关抑癌基因
CDH1、 RB和 E2F5表达上调恢复。
临床研究应用免疫组织化学法和RT-PCR技术分别从蛋白水平和基因水平
检测证实MBD1在胰腺癌临床标本中的表达,并观察区域性动脉灌注化疗对
MBD1表达的影响,研究结果表明MBD1蛋白在胰腺癌中的表达(阳性率 76.32%)
明显高于正常胰腺、癌旁、慢性胰腺炎和胰腺良性肿瘤组织;RT-PCR同样显示
MBD1mRNA在胰腺癌组织中的表达明显高于正常胰腺组织和癌旁对照组织
(P<0.01)。MBD1的表达水平的高低与性别、年龄、肿瘤部位、肿瘤
大小、分化程度和TNM分期之间无显著性差异;而有淋巴结转移的胰
4
博士论文 第 5 页 共 100 页
腺癌MBD1表达(阳性率92.31%)明显高于无淋巴结转移者(41.67%),
其中7例强阳性表达的胰腺癌病理证实均有16组(腹主动脉旁)淋巴
结的转移,说明MBD1与胰腺肿瘤转移和侵袭活性密切相关,检测
MBD1对预测胰腺癌患者的预后有指导作用。区域动脉灌注介入化疗
能明显抑制MBD1基因的表达(P<0.01)。
总之,研究表明MBD1在胰腺癌中的表达明显增高,并与胰腺癌转移侵
袭活性相关,是致癌密切相关基因。MBD1siRNAs能抑制胰腺癌AsPC-1细
胞株MBD1的表达及其增殖能力,并可上调其它甲基化相关抑癌基因
表达,MBD1可能成为一个新的基因治疗靶点。区域性动脉灌注化疗
明显抑制MBD1基因的表达,是一有效的临床治疗措施。
As an important transcription factor, methyl-CpG binding domain protein
1 (MBD1) mediated transcription-suppressing course and might cause descent
expression of numerous tumor suppressor genes, or even result in devitalization of
those genes. The expression and role of MBD1 were studied in experimental and
clinical part respectively.
Experimental study: MBD1 mRNA expression level was detected in two
pancreatic cancer cell lines, AsPC-1 and BxPC-3, by method of RT-PCR. The
expression of MBD1 was very high in two cell lines. BxPC-3 was cultured from
pancreatic carcinoma in situ, while AsPC-1 was cultured from the ascites of a late
stage patient. AsPC-1 not only had strong metastasis vitality but also had biological
character of the primary cancer. We choose AsPC-1 as our further research patform.
By RNA interference (RNAi) technology, the siRNA was designed and
synthesied which aimed at the MBD1 gene. BgLⅡand HindⅢ restriction enzyme
sites were introduced into the 5’ and 3’of MBD1 gene siRNAs respectively, then
inserted into polylinker site of plasmid Rotro Super, MBD1 siRNAs eukaryotic
expression vector Rotro Super-MBD1 was constructed. MBD1 siRNAs had been
successfully integrated into the plasmid. MBD1 siRNAs vector was transfected into
pancreatic cancer cell AsPC-1 by liposome. Positive clone was obtained by the screen
of G-418.
MBD1 expression level was detected by RT-PCR, and MBD1 protein was tested
by western-blot, growth curve MTT assay and clony forming test were used to assess
the proliferation potency. Multi-dots gene chip was used to detect the expression level
of methylation related cancer suppressor genes. It was demonstrated that MBD1
siRNAs could significantly suppress expression of MBD1 mRNA in AsPC-1, which
was the same for protein expression. Growth curve and clony forming test show that
cell growth is significantly inhibited. It demonstrates that MBD1 siRNAs can inhibit
the proliferation of pancreatic cancer cells, reduce its survival ability and adaptability.
The methylated cancer suppressor genes, such as CDH1, Rb and E2F5 were
up-regulated in the multi-dots gene chip experiment.
The expression of MBD1 in pancreatic carcinoma was detected at protein level
by immunohistochemistry, at gene level by RT-PCR respectively. MBD1 expression
was significantly higher (76.32%) in pancreatic carcinomas than that in normal
pancreatic tissue, benign pancreatic tumors, corresponding distant pancreas tissues
6
博士论文 第 7 页 共 100 页
and chronic pancreatitis measured by immunohistochemistry. The expression of
MBD1 mRNA in pancreatic carcinomas was also obviously higher than normal
pancreatic tissues, or the distant pancreatic tissues (P<0.01) tested by RT-PCR. No
correlation was found between the expression of MBD1 with the sex, age, location,
size, differentiation or the staging of pancreatic carcinoma. MBD1 expressed in
92.31% pancreatic carcinomas with lymph node metastasis, which is higher than that
in pancreatic carcinomas without lymph node metastasis (41.67%). Among them, 7
samples with MBD1 strongly expressed were testified having para-abdominal aorta
lymph node metastasis (station 16). The influence of intra-arterial chemotherapy on
MBD1 gene expression was also studied. MBD1 gene expression declined after
intra-arterial chemotherapy.
Conclusion: the expression level of MBD1 was significantly higher in pancreatic
carcinoma and it might have close correlation with metastasis of pancreatic cancer.
MBD1 was one of the oncongenes of pancreatic carcinoma. MBD1 siRNAs could
inhibit the expression of MBD1 and the proliferation of pancreatic cancer cells
AsPC-1, up regulating expression level of other methylated cancer suppressor genes,
and MBD1 may be a new target of gene therapy for pancreatic carcinoma. Regional
intra-arterial chemotherapy was an effective treatment by inhibiting the expression of
MBD1.
引文
[1]Schutte-M, Hruban-RH, Geradts-J, et al. Abrogation of the Rb/p16
tumor-suppressive pathway in virtuaLLy all pancreatic carcinomas Cancer
Research 1997;57:3126-3130
[2] Bouvet-M, Bold-RJ, Lee-J, Evans-DB, et al. Adenovirus-mediated wild-type p53
tumor suppressor gene therapy induces apoptosis and suppresses growth of human
pancreatic cancer. Ann Surg-Oncol, 1998;5(8):681-688
[3] Hwang-RF, Gordon-EM, Anderson-WF, et al. Gene therapy for primary and
metastatic pancreatic cancer with intraperitoneal retroviral vector bearing the
wild-type P53 gene. Surgery 1998;124(2):143-150
[4] Joshi-US, Dergham-ST, Chen-YQ, et al. Inhibition of pancreatic tumor cell growth
in culture by P21WAF1 recombinant adenovirus.Pancreas 1998;16(2):107-113
[5] 张群华,倪泉兴,傅德良,姚琪远等. P19基因转染胰腺癌细胞生长和凋亡的研究.
首届全国胰腺癌早期诊断和综合治疗新近展学术研讨会论文集 1999;34
[6] Simeone DM, Cascarelli A, Logsdon CD. Adenoviral-mediated gene transfer of a
constitutively active retinoblastoma gene inhibits human pancreatic carcinoma
cells. Oncogene 1998;16:1593-1602
[7] Grau-AM, Zhang-L, Wang-WX, et al. Induction of p21waf1 expression and
growth inhibition by tramsforming growth factorβ involve the tumor suppressor
gene DPC4 in human pancreatic adenocarcinoma cells. Cancer Research.
1997;57:3929-3934
[8] Cerutti-J, Trapasso-F, BattagLia-C, et al. Block of c-myc expression by antisense
oligonucleotides inhibits proliferation of human thyroid carcinoma cell lines. Clin
Cancer Research, 1996;2:119
[9] Kita-K-I, Satio-S, Morioka-CY, et al. Growth inhibition of human pancreatic
cancer cell lines by anti-sense oligonucleoltides specific to mutated K-ras genes.
Int-J-Cancer, 1999;80(4):553-558
[10] Bergmann-U, Funatomi-H, Yokoyama-m, et al. Insulin-like growth factor Ⅰ
overexpression in human pancreatic cancer:Evedence for autocrine and paracrine
roles. Cancer Research. 1995;55:2007-2011
[11] Cheng JQ, Ruggeri B, KLein WM, et al. Amplification of AKT2 in human
pancreatic cells and inhibition of AKT2 expression and tumorigenicity by
antisense RNA. Proc Natl Acad Sci USA. 1996;93:3636-3641
[12] Rosenfeld ME, Vicker SM, Raben D, et al. Pancreatic carcinoma cell killing via
84
博士论文 第 85 页 共 100 页
adenoviral mediated delivery of the herps simplex virus thymidine kinase gene.
Ann Surg. 1997;225:609-620
[13] Carrio-M, Romagosa-A, Mercade-E, et al. Enhanced pancreatic tumor regression
by a combination of adenovirus and retrovirus-mediated delvery of the herps
simplex virus thymidine kinase gene. Gene-Ther 1999;6(4):547-553
[14] Ohashi-M, Kanai-F, Tanaka-T, et al. In vivo adenovirus-mediated prodrug gene
therapy for carcinoembryonic antigen-producing pancreatic cancer.
Jpn-J-Cancer 1998;89(4):457-462
[15] Evoy D, Hirschowitz EA, Naama HA, et al. In vivo adenoviral-mediated gene
transfer in the treatment of pancreatic cancer. J Surg Res. 1997;69:226-231
[16] McNeish-IA, Green-NK, GriLLigan-MG, et al. Virus directed enzyme prodrug
therapy for ovarian and pancreatic cancer using retriovirally delivered E.Coli
nitroreductase and CB1954. Gene-Ther, 1998;5(8):1061-1069
[17]Itoh Y, Koshita Y, Takahashi M, et al. Characterization of
tumor-necrosis-factor-gene-transduced tumor in filtrating lymphocytes from
ascific fluid of cancer patients:analysis of cytolytic activity growth rate adhesion
molecule expression and cytokine production. Cancer Immunol Immunotherapy.
1995;40:95-102
[18] Sato T, Yamauchi N, Sasaki H, et al. An apoptosis-inducing gene threapy for
pancreatic cancer with a combination of 55-Kda tumor necrosis factor(TNF)
receptor gene transfection and mutein TNF administration. Cancer Res.
1998;58:1677-1683
[19] Kimura-M, Tafawa-M, Takenaga-K, et al. Loss of tumorigenicity of human
pancreatic carcinoma cells engineered to produce interleukin-2 or interleukin-4 in
nude mice :a potentiality for cancer gene therapy. Cancer-Lett.
1998;128(1):47-53
[20] Yoshida-Y, Tasaki-K, Kimura-M, et al. Antitumor effect of human pancreatic
cancer cells transduced with cytokine genes which activate Th1 help T cells.
Antt-Cancer-Res. 1998;18(1):333-335
[21] PeoLinski GR, Tsung K, Meko JB, et al. In vivo gene therapy of a murine
panceas tumor with recombinant vaccinia virus encoding human interleukin-1
beta. Surgery. 1995;118:185-191
[22] Rochaix-P, DeLesque-N, Esteve-J-P, et al. Gene therapy for pancreatic carcinoma:
local and distant antitumor effects after somastatin receptor sst2 gene transfer.
85
博士论文 第 86 页 共 100 页
Hum-Gene-Ther, 1999:10(6):995-1008
[23] Wagner-M, Lopes-ME, Cahan-M, et al. Suppression of fibroblast growth factor
receptor signaling inhibits pancreatic cancer growth in vivtro and in vivo.
Gastroenterology. 1998;114:798-807
[24] Kaiser-A, Herbst-H, Fisher-G, et al. Retinoic acid receptor beta regulates growth
and differentiation in human pancreatic carcinoma cells. Gastroenterology.
1997;113:920-929
[25] SeufferLein-T, Lint-JV, Lipty-S, et al. Transforming growth factor-α activate
Ha-Ras in human pancreatic cancer cells with Ki-ras mutations.
Gastroenterology. 1999;116:1441-1452
[26] Lyon MF. Imprinting and X chromosome inactivation. Result Probl Cell Differ,
1999,25(8):73-90.
[27] Peter WL, RudoLf J. The role of DNA methylation in cancer genetics and
epigenetics. Aunn Res Genet, 1996,30(9):441.
[28] Bender CM, Zingg JM, Jones PA. DNA methlation in bladder cancer. Pharm
Aceutical Res,1998,15(2):175.
[29]Ahujia N, Agingand. DNA methylation in colorectal mucosa and cancer. Cancer
Res, 1997,58(23):3370- 3374.
[30]Wheeler JM, Beck NE, Kim HC, et al. Mechanisms of inactivation of mismatch
repair genes in human colorectal cancer cell lines: the predominant role of Hmlh1.
Proc Natl Acad Sci,1999,96(18):10296 -10301.
[31]Ng HH, Bird A. DNA methylation and chromatin modification. Curr Opin Genet
Dev,1999,9(2):158 -163.
[32]Costello JF, Fruhwald MC. Aberrant CpG island methylation has non random and
tumour type specific patterns. Nat Genet ,2000,24(2):132-138.
[33]Cody DT, Huang Y. Differential DNA methylation of the p16INK4 CDKA2 a
promoter in human oral cancer cells and normal human oral kerarnocytes. Oral
Oncol,1999,35(5):516 -522.
[34]白晓川,白志勇,武淑兰,等.8 种肿瘤细胞系降钙素甲基化模式及其与甲基转移
酶活性的关系[J].癌症,2001,20(2):156 -159.
[35]于力,王全顺,顾群,等.白血病细胞多巴胺受体基因甲基化研究[J].军医进修学
院学报,2000,13(4):186-190.
[36]Liu M, Taketani T, Li R, et al. Loss of p73 gene expression in lymphoid cell lines
is associated with hypermethylation. Leuk Res,2001,25(6):441 447.,21(1):62-64.
86
博士论文 第 87 页 共 100 页
[37]Stirzaker C, Millar DS, Paul CL. Extensive DNA methylation spanning the Rb
promoter in retinoblastoma tumors. Cancer Res, 1997,57(11):2229-2237.
[38]Nass SJ, Herman JG, GabrieLssen E, et al. Aberrant methylation of the estrogen
receptor and E-cadherin 5’CpG islands increases with malignant progression in
human breast cancer. Cancer Res, 2000,60(16): 4346-4348.
[39]Esteller M, Corn PG, RayLin SB, et al. A gene hypermethylation profile of human
cancer. Cancer Res, 2001, 61(8):3225-3229.
[40]Guru T.A silence that speaks volume。Nature,2000404。804-808.
[41] Guo S, Kempheus KJ. a gene required for establls-hing polarity in Celegans
embryos encodes a putativeSer / Thr klnase that is asymmetrically
dlstributed .Cell,1995,81(4):611-620.
[42]Fire A, Xu S, MeLLo CC, et al. Potent and specific geneticinterference by
double-stranded RNA in caenorhabditis elegans.Nature,1998,391:806-811.
[43]Hammond S,Bernstein E,Hannon G,et al. An RNA-directed nuclease
mediates post-transcriptional gene silencing in drosophila cells. 2000,404
(6775):293-298
[44]Elbashir SM, Lendeckel W, Tuschi T. RNA interference is mediated by 21-and
22-nucleotides RNAs. Genes, 2001,13(2):188-200.
[45]Sayda M,Elbashir,Winfried,et al. Duplexes of 21-uncleotideRNAs mediate
RNA interference in culturedmammalian cells. Nature,2001,411-494.
[46]Hutvagner G,Zamore PD. RNAi:nature abhors a double-strand. Curr Opin
Genetics and Development,2002,12:225-232
[47]Sharp PA, RNA Interferenc. 2001.Genes Dev.2001,15:485-490
[48]Lipardi C,Wei Q,Paterson BM.RNAi as randonm degradative PCR:siRNA
primers convert mRNA into dsRNAs that are degraded to generate new siRNAs.
Cell,2001,107:297-307
[49]Holen T, Amarzguioui M, Prydz H, et al. Positional effects of short interferning
RNAs targeting the human coagulation trigger tissue factor. Nucleic Acids Res,
2002,308:1757-1766.
[50]Miyagishi M, Taira K. U6-promoter-driven siRNAs with four uridine 3’overhangs
efficiently suppress targeted gene expression in mammalian ceLLs. Nature
Biotechnol, 2002,20:497-500.
[51]Brummelkamp TR, Bernards R, Agami R. A system for stable expression of short
interfering RNAs in mammalian cells. Science,2002, 296:550-553.
87